"I have decided to run for re-election," the Arizona senator told NBC News in an exclusive interview revealing his plans to pursue a sixth term on Capitol Hill. "I'm ready. I am more than ready. In some ways, I am eager."

McCain is currently 78 years old but will be 80 by Election Day in 2016. He defended his vitality, saying that he is “just getting started” when it comes to his Senate career.

"I say watch me,” he said. “Take a look. Take a look at my 18 hour days. Take a look at the hearings we have. Take a look at my legislative accomplishments.”

With a smile, McCain also cited the longevity of his mother, Roberta. “I am happy to tell you my mother is 103 years old and she is doing well,” he said.

McCain finally landed a dream job this year as chairman of the Senate Armed Services Committee. From that perch, he can continue the committee’s long tradition of bipartisanship. But the post also gives McCain an even bigger megaphone on national security, which he uses often to criticize President Barack Obama.

“I have never been more concerned about the security of this nation because of the feckless leadership of the president of the United States,” he said.

After winning the Republican Party’s nomination for president in 2008, McCain has faced anger from conservatives who saw him as too moderate.

Tea Party groups see him as a top target for a primary challenge. Last year, Arizona’s state Republican Party censured McCain as too liberal, but today he says his home state relationships “have improved significantly.”

“I was also censured by Vladimir Putin,” he noted with a laugh.

McCain’s Senate re-election campaign will come during another high-stakes presidential cycle. He supports good friend South Carolina Sen. Lindsey Graham for the GOP nod, although he acknowledges that Graham is a “dark horse.” Despite his friendship with Hillary Clinton, McCain says the potential Democratic nominee lacked an impressive record while serving at the helm of the State Department.

“I think that a legitimate question to Hillary Clinton is, ‘What did you accomplish during your four years as secretary of state? Except that you visited more countries than any other previous secretary of state. What was your accomplishment?’ he said. “So far, I don’t know what an answer to that would be.“

To win his own re-election, McCain said he will stress home state issues, including Arizona’s drought, his work to benefit a local copper mine and his bipartisan legislation to reform the Department of Veterans Affairs after scandal at Phoenix VA Medical Center.

"I have to convince the voters all over again of Arizona,” he said. “But I will stand on my record but more so, I will stand on what I can do for Arizona and the nation."